<?php

namespace app\Admin\controller;

use think\Controller;

class Demo
{
    private static $instance;

    private function __construct()
    {

    }

    private function __clone()
    {
        // TODO: Implement __clone() method.
    }

    public static function getInstance(){
        if(!self::$instance instanceof self){
            self::$instance = new self();
        }
        return self::$instance;
    }

}
